IPv6 or Internet Protocol Version 6 is the next generation protocol for the Internet. It's designed to provide several advantages over current Internet Protocol Version 4 (or IPv4).

Both IPv6 and IPv4 define network layer protocol i.e., how data is sent from one computer to another computer over packet-switched networks such as the Internet.

Specifically, IPv6 contains addressing and control information to route packets for the next generation Internet.We believe that the expansion of the Internet is important and upgrades are sometimes warranted.

Gathering information concering every aspects of IPv6 we would hope to provide knowledge about this technology so everyone can benefit.
It is therefore also called the Next Generation Internet Protocol or IPng .

IPv6 is documented in several RFCs (or request for comments) starting from RFC 2460. Although IPv6 is the successor of IPv4, both protocol versions will continue to be data-oriented protocols for the Internet in the coming years.

Why IPv6?

IPv6 addresses the main problem of IPv4, that is, the exhaustion of addresses to connect computers or host in a packet-switched network. IPv6 has a very large address space and consists of 128 bits as compared to 32 bits in IPv4.

Therefore, it is now possible to support 2^128 unique IP addresses, a substantial increase in number of computers that can be addressed with the help of IPv6 addressing scheme.

In addition, this addressing scheme will also eliminate the need of NAT (network address translation) that causes several networking problems (such as hiding multiple hosts behind pool of IP addresses) in end-to-end nature of the Internet.

Qos

IPV6 brings quality of service that is required for several new applications such as IP telephony, video/audio, interactive games or ecommerce. Whereas IPv4 is a best effort service, IPv6 ensures QoS, a set of service requirements to deliver performance guarantee while transporting traffic over the network.

For networking traffic, the quality refers to data loss, latency (jitter) or bandwidth. In order to implement QOS marking, IPv6 provides a traffic-class field (8 bits) in the IPv6 header. It also has a 20-bit flow label.

Mobile IPv6

This feature ensures transport layer connection survivability and allows a computer or a host to remain reachable regardless of its location in an IPv6 network and, in effect, ensures transport layer connection survivability.

With the help of Mobile IPv6, even though the mobile node changes locations and addresses, the existing connections through which the mobile node is communicating are maintained.

To accomplish this, connections to mobile nodes are made with a specific address that is always assigned to the mobile node, and through which the mobile node is always reachable. This feature is documented in RFC 3775.

Other important features of IPv6:

Stateless Auto-reconfiguration of Hosts
This feature allows IPv6 host to configure automatically when connected to a routed IPv6 network.